LB 7-56 - Adaptation measures timeline for conservation and sustainable use of forest resources under uncertainty future

The objective of this study is to identify timelines for adaptation measures that promote the conservation and sustainable use of forest resources under climate change. The study aims to examine how sustainable management of forest resources can be achieved under conditions of high uncertainty, such as climate change, economic fluctuations, and demographic change, and to provide a timeline of effective timing and irreversible tipping points for adaptation measures.The target area covers approximately 250 sq km, including diverse landscapes such as cities, rice paddies, and forests in the northern Kyushu region of Japan. Spatial and temporal distributions of planted forest stand growth and landslide risk were projected for three time periods (2030s, 2050s, and 2080s) under multiple climate scenarios and representative concentration pathways (RCPs). A planted forest stand growth model and a model of the frequency of landslide-causing heavy rainfall events were used for the predictions. Based on the predicted results, four potential land-use maps were developed: two cases maximizing timber production and landslide damage reduction respectively, two balancing cases, and a status quo case. Land-use modifications according to each case were defined as adaptation measures, and the limiting factors for the implementation of adaptation measures were the limitation of modification in areas with high biodiversity, depletion of social and human resources due to population decline, and limitation of transportation due to aging infrastructure. The percentage of area that could be modified, taking into account the limiting factors, was assessed as the degree of achievement against the optimal adaptation measures. The point at which the level of achievement fell below 25% was considered the tipping point, and its period was recorded.Tree height growth was predicted to change growth type patterns across the target area from the 2030s, but only in a limited number of locations where growth decline was predicted. On the other hand, landslide risks were predicted to increase in parts of the target area from the 2050s onwards. For both growth and landslide risk projections, uncertainty in projections due to climate scenarios and RCPs increased from the 2050s onwards. The projected decline in the effectiveness of adaptation measures and the increase in uncertainty towards the latter part of the period suggest that earlier adaptation measures may be more effective.